Forge furnace



Jan. 1, 1957 J. D. NESBITT ETAL FORGE FURNACE 2 Sheets-Sheet 1 F118;: Oct. 50,- 1953 INVENTOR JD Nesblff BY 71% Nun fora m J? Jan. 1, 1957 J. D. NESBITT ETAL 2,776,128

FORGE FURNACE Filed Oct. 50, 1953 2 Sheets-Sheet 2 INVENTOR 5'57 12 J17. Nash/ff BY TM/Vunfiw'd United States Patent-- FORGE FURNACE John D. Nesbitt, Sylvania, and Theodore W. Munford,

Toledo, Ohio, assignors to Surface Combustion Corporation, Toledo, Ohio, a corporation of Ohio Application October 30, 1953, Serial No. 389,302

2 Claims. (Cl. 263- 6) This invention relates to forge furnaces, and more particularly to skid rail work supports therefor and means for providing more uniform temperatures in the work discharged from the furnace.

Heretofore difficulties are have encountered in obtaining a maximum uniformity of temperature in work pieces pushed end to end through a high heat head heating furnace on water cooled skid rails. The very high heat head which makes these furnaces so desirable by reducing heating time and scale formation precludes time at temperature to soak out hot or cool spots in the work. The internally cooled skid rails produce some locally cooler regions on the work which in certain cases must be removed before hot Working.

This problem of cold spots resulting from work supports has been solved by provision of an underfired, openwork refractory discharge hearth which is preferably fired independently of the furnace fast heating zones and by extension of the rails into shadow rail sections which at the discharge end of the furnace move out of contact with the work but into a shielding position between the upper side of the work and the hot furnace wall, whereby work which reaches the desired discharge temperature faster on the top thereof may be prevented from overheating by the shielding of the shadow rails While cooler portions are brought to temperature by underfiring the refractory openwork discharge hearth.

For a further consideration of what we believe to be novel and our invention, attention is directed to the following portion of this specification, the drawing, and the claims forming part thereof.

In the drawing:

Fig. l is a longitudinal vertical section of a furnace embodying the present invention.

Fig. 2 is a transverse sectional view of the furnace on line 2--2 of Fig. 1.

Fig. 3 is a transverse sectional view of the furnace on line 33 of Fig. 1.

Fig. 4 is a plan view of a portion of the support rails for the furnace of Fig. 1.

Fig. 5 is an elevational view of the details of Fig. 4.

Fig. 6 is a plan view of the support rails for the furnace of Fig. 1.

Fig. 7 is an elevational view of the rails of Fig. 6.

Fig. 8 shows a plan view of part of the discharge hearth portion of the furnace of Fig. 1.

Figs. 9, 10, 11 and 12 show a sectional view of the discharge hearth on lines 9-9, 1010, 11-11 and 12-12, respectively, of Fig. 8.

In the furnace illustrated, work is heated to the desired temperature by supporting it on internally cooled skid rails in the first, or fast heating zone and applying a high heat head to the work until the work approaches the desired temperature, at which time it is advanced from the first to the second, or temperature equalizing, zone onto a refractory openwork hearth where the lower surfaces of the work, which were kept locally relatively cool by "ice the skid rails, are heated by burners arranged to fire into the openwork hearth, while the upper surfaces are protected from overheating by internally cooled shadow rails. As the work reaches substantially equalized temperature in the second, or equalizing, zone it is discharged from the furnace.

The furnace forms a two zone heating chamber divided by a refractory arch, with individual heating means for each zone and a flue for each zone. The work is supported on internally cooled skid rails in the first zone and on an axially aligned refractory openwork hearth in the second zone, and the rails extend from end to end through the heating chamber, being offset in the second zone from the skid portions in the first zone whereby to form shadow rail portions in the second zone and protect the adjacent work thereunder from overheating.

The furnace comprises a refractory lined tunnel 20 forming a cylindrical furnace heating chamber wherethrough work is advanced for heating. The tunnel 20 is supported by laterally extending arms 21 atop rails 22 which in turn rest on pillars 23. Work W to be heated is advanced through the furnace chamber by a charging mechanism 24 which periodically pushes work pieces into the furnace chamber onto internally cooled support skid rails 25. The rails 25 are supported at intervals on bridge piers 26 within the furnace chamber, and support the work through the major portion of the furnace. Towards the discharge end of the furnace the work is pushed off from the internally cooled rails 25 onto refractory supports 27, from which it is discharged onto a discharge chute formed by internally cooled skid rails 28.

The furnace chamber is functionally divided into a fast heating section and a temperature equalizing section. In the fast heating section, the internally cooled rails 25 are supported oif the refractory piers by tubular connectors 31, 32 through which coolant is forced to flow. These connectors are so connected as to force a cross flow of coolant from each rail upstream of the connectors, through a connector and to the other rail downstream of the connectors. This is preferably accomplished by a restriction or plug 33 in each rail between the connections for the tubular connectors. Heat is supplied to the fast heating portion of the furnace by burning premixed fuel and air from fuel manifolds 34, 35 delivered tangentially to the furnace refractory lining at very high velocity by nozzles 36. Fully aerated fuel leaves the nozzles 36'through ports 37, enters tangentially upon the refractory lining and burns thereon to constitute the same a source of radiant heat tending to overheat the work. Products of combustion pass towards the center of the chamber and scrub the work as they move towards the respective ends of the furnace where they are discharged through flues 41, 42.

The fast heating and the equalizing zones are divided by an arch 43 which reduces the effect of radiation of heat from the walls of the fast heating zone to work in the equalizing zone. Work in the equalizing zone is supported on refractory shapes forming Work supports 27 and apertures 44. The internally cooled rails 25 are formed with an offset portion 45 at the discharge hearth serving to shield the work from the hot refractory wall thereabove and from the hot gases passing from the fast heating chamber, under the arch 43 and through the discharge end flue 42. Heat is applied through the refractory openwork support at the discharge equalizing section by burners 53, supplied with premixed fuel and air from fuel manifold 47, the burners being directed to deliver combustion products towards the apertures 44 under the refractory work supports 27. The underside of the work is thus brought to heat where its heating had been retarded 3 somewhat by the adjacent internally cooled skid rails 25. The discharge hearth is set apart from the fast heating part of the furnace by the arch 43, and by shielding the work from above and applying heat from below, the

work temperature is equalized before dischargefrom the furnace. The work shielding isaccomplished by peculiarly formed internally cooled rails 25 which in the fast heating zone support the work, but in the temperature equalizing zone prior to discharge these rails are shaped to pass over the top faces of the Work. Thus the great advantages of a coupled pair of rails for work support with coolant inlets and outlets only at the ends of the rails, are retained, yet an additional function is performed by the rails. These rails may be easily removed for servicing or replacement, and only one end thereof need be passed'through refractory walls, thus eliminating relative expansion problems between furnace shell, lining, and rails.

As shown in Figures 11 and 12 which show a portion of the adjacent refractory support 27,. as illustrated in Fig. 3, in adidtion to the portions indicatedby lines 11 -11 and 12-12 of Fig. 8, the refractory open work supports 27' are preferably formed by refractory shapes supported by bricks 51 placed on edge and spaced by bricks 52 placed on their sides, thus providing apertures 44 through which burners 53 may direct their flames. The burners 53 are disposed in the side wall of the equalizing portion of the furnace and arranged to fire onto the flat bricks 52 to direct hot gases through the apertures 44 andundcr the work to heat. the refractory supports 27 and the work on the cooler side thereof.

We claim:

1. In a high heat head furnace for rapidly heating work to-hot working temperature, in-combination: wall. means.

forming first and second heating zones; skid rail structure consisting of a pair of water cooled pipes extending end to end through said furnace and means for maintaining said pipes in spaced relationship, said pipes forming a first, parallel section in the first heating zone spaced and adapted to serve as a support for work passing along a path through the furnace, and a second, parallel section contiguous to saidfirstsection and in which the pipes are offset toa position above and adjacent said'path to serve as shadow rails for protecting work advancing through the furnace along said path; means for applying a high heat head to the work in said first zone; and refractory means insaid second heating zone for supporting the work as it moves therethrough along said path.

2. In a furnace according to claim 1, in combination; burner means for selectively applying heat to the lower portion of work in the second heating zone as it passes along said path, whereby said rails prevent overheating of the upper portion of the work in the second. zone while the burner means heats the lower portion in said zone to the same temperatures at discharge as the upper portion.

References Citedin the file of this patent UNITED STATES PATENTS 

